Engine starter gearing



Dec. 6, 1960 J, E, BUXTQN 2,962,902

ENGINE STARTER GEARING Filed Jan. 26, 1959 56 57 58 "A 6 iii/{29.3% 35 55 $2.39 1

INVENTOR. WITNESS: .jmws 3 Km. 5x272: [4321;

TTORNE 2 United States Patent ENGINE STARTER GEARING James E. Buxton, Elmira, N.Y., assignor to The Bendix Corporation, a corporation of Delaware Filed Jan. 26, 1959, Ser. No. 789,068

6 Claims. (Cl. 74-7) The present invention relates to engine starter gearing and more particularly to a double reduction drive of the 1 type in which the drive pinion is traversed automatically into and out of mesh with a gear of the engine to be started.

In automotive progress the evolution of the electric starting motor to progressively smaller units energized by gears objectionably large in respect to road clearance and body design. The logical path for further progress is the adoption of some form of double-reduction drive such as shown for instance in the patents to Bendix 1,327,303, issued January 6; 1920, and Whitney 1,396,- 695, issued November 8, 1921.

Double-reduction drives have not heretofore been widely adopted, however, owing to failure to meet the exacting requirements of the automotive industry in respect to performance and cost. Moreover, in drives of the above type which embody speed reduction gearing between the motor shaft and the pinion shaft, special provisions are necessary to traverse the pinion since the acceleration of the pinion shaft is not suificient to reliably perform this function.

It is an object of the present invention to provide a novel double reduction engine starter drive which is efiicient and reliable in operation, and simple and economical in construction.

It is another object to provide such a device in which the reduction gearing is continuously in mesh, and the drive pinion is connected to the low-speed gear through an automatically controlled overrunning clutch.

It is another object to provide such a device in which the automatic traversal of the pinion is assisted by traversing means mounted on the motor shaft.

It is another object to provide such a device including a yielding driving connection from the low speed gear to the drive pinion, and a frictional rotary connection between the traversing means and the drive pinion.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing in which the figure is a side elevation, partly broken away and in section of a preferred embodiment of the invention.

In the drawing there is illustrated a motor shaft 1 which is preferably the extended armature shaft of the starting motor 2, on which a driving gear 3 is rigidly mounted in any suitable manner. The driving gear 3 meshes with a driven gear 4 of suitably larger diameter which is fixedly mounted on a pinion shaft 5 which is thus rotated at a reduced speed. The shafts 1 and 5 are rotatably mounted in parallel relation by means of bearings 6, 7, 8 and 9 in an outboard housing 11 attached to the starter motor 2.

The shaft 5 has a pinion 12 slidably journalled there- 2,962,902 Patented Dec. 6, 1960 ice on for movement into and out of mesh with a gear 13 0f the engine to be started. Means for actuating the pinion 12 from the shaft 5 is provided comprising a screw shaft 14 slidably journalled on the pinion shaft 5 hav ing overrunning clutch teeth 15 engaging similar teeth 16 on a driving disc 17. The disc 17 is rotated by the driven gear 4 by means of a ring 18 of elastically deformable material such as rubber, which ring is seated in an annular groove 19 in the face of the driven gear 4 and is maintained under initial compression between the gear 4 and disc 17 by means of a spring 21 interposed between the end of the screw shaft 14 and an abutment ring 22 fixedly mounted on the pinion shaft 5.

A control nut 23 is threaded on the screw shaft 14, and a barrel member 24 is anchored at one end to the control nut as indicated at 25 and at its other end has a splined connection with the pinion 12 as shown at 26. The pinion 12 is yieldably maintained in extended relation to the barrel by means of a mesh-enforcing spring 27 bearing at one end on the control nut 23 and at its other end against a flange member 28 fixedly mounted on the end of pinion 12. The idle position of the pinion as illustrated is defined by the ends of the threads on; the screw shaft 14 which limit the travel of the control nut 23 away from the engine gear 13. The meshing movement of the pinion is limited by the abutment ring 22 which arrests the control nut, after which the screw shaft 14 is forced back by screw-jack action, causing the drive disc 17 to compress the rubber ring 18 against the gear 4. Said ring thus acts as a yielding coupling member between the gear 4 and disc 17 If deemed desirable to increase the adhesion of the rubber ring to the gear and disc, it may be bonded to said members in conventional manner.

Means for traversing the pinion and barrel assembly to move the pinion into and out of mesh with the engine gear 13 is provided comprising a screw shaft 29 fixedly mounted on the driving shaft 1 as by means of the set screw 31, and a traversing nut 32 threaded on the screw shaft 29.

The barrel member 24 has a ring 33 rigidly mounted thereon. The traversing nut 32 has a flange 34 formed thereon and an annular member 35 slidably mounted thereon. The flange 34 and annular member 35 are adapted to bear on opposite sides of ring 33, frictional washers 36, 37 being preferably interposed, and are maintained in frictional relation with the ring 33 by means of a spring member 38 bearing against the annular member 35. An anti-drift spring 39 is seated at one end on an abutment 41 fixed on the motor shaft 1, and at its other end cooperates with a thrust washer 42 to urge the traversing nut 32 to its idle position as illustrated.

In operation, starting with the parts in the positions illustrated, acceleration of the motor shaft 1 causes the traversing nut 32 to move to the right on screw shaft 29, carrying with it the pinion and barrel assembly 12, 24 by means of the ring 33 until the pinion 12 is meshed with the engine gear 13, which mesh-ing position is de fined by the abutment member 22 which arrests the meshing movement of the control nut 23.

At the same time the pinion shaft 5 is being rotated by the driven gear 4, so that the traversal of the pinion and barrel assembly is assisted by the reaction of the screw shaft 14 with the control nut 23, these members being preferably of a substantially higher pitch than the screw shaft 29 and traversing nut 32. Further rotation of the motor shaft 1 causes the pinion 12 to crank the engine with torque multiplied by the gear reduction ratio between the motor shaft 1 and the pinion shaft 5.

It will be understood that during cranking some ro, tary slippage may take place between the traversing nut 32 and the ring 33 on barrel member 24 depending upon the ratio of their engaging surfaces as compared to the ratio of gears 3 and 4. The spring 38 may, however, be made sufiiciently light so that the friction so generated is negligible.

When the engine starts, the pinion and barrel assembly overruns the disc 17 on the pinion shaft; 5, and the ring 33 rotates the traversing nut 32 faster than themotor shaft 1, whereby the traversing nut; together with the pinion and barrel assembly are moved back to idle position in which position they are yieldably maintained by the anti-drift spring- 39.

Although but one embodiment of the invention has been shown and described in detail it will be understood that changes may he made in the design and arrangement of the parts withoutdepartin'g from the spirit of the invention.

I claim:

1. In a double-reduction engine starter drive a motor shaft, a pinion shaft, a driving gear fixedly mountedon the motor shaft, a driven gear fixedly mounted on the pinion shaft meshing with the driving gear, a threaded sleeve rotatably mounted on the pinion shaft, a yielding overrunning clutch connection from the driven gear to said sleeve, a control nut threaded on the sleeve, a pinion slidably journalled on the pinion shaft for movement into and out of mesh with a gear of the engine to be started, means including a barrel member connecting the control nut to the pinion, and traversing means mounted on and responsive to acceleration of the motor shaft for traversing the pinion into mesh with the, engine sear.

' 2. {A double-reduction starter drive as set forth in claim 1 in which said traversing means includes a hollow screw shaft'fixedly mounted on the motor shaft, a nut threaded thereon, and means connecting the last mentioned nut to said barrel member for longitudinal movement in unison.

3. A starter drive as set forth in claim 2 in which the means for connecting the nut on the motor shaft to the barrel member includes a frictional rotary connection therebet ween,

4. A starter drive as set forth in claim 2 including further yielding means urging the nut on the motor shaft toward idle position.

5. A starter drive as set forth in claim 1, in which the connection from the driven gear to the threaded sleeve includes a clutch member slidably mounted on the pinion shaft, said clutch member and sleeve having co operating overrunning clutch teeth, a yielding thrust and driving connection from the driven gear to the clutch member, and an abutment limiting the meshing movement of the control nut to thereby cause the screwjack action of the sleeve and control nut under load to force the sleeve against the clutch member.

6. A starter drive as set forth in claim 1 in which the barrel member is splined to the pinion, and the means for connectingthe control -nut to the pinion includes a compression mesh-enforcing spring.

References Cited'in the file of this patent; UNITED STATES PATENTS -.-.'.-,-.-tr--e-ee P FOREIGN PATENTS 176,114 Great Brita Feb- 2 1 2 

